Age-related changes in bioelectric activity of the trophotropic zone of hypothalamus in rats

V. V. Mukvych, V. P. Lyashenko, S. M. Lukashov

Abstract


Introduction. Due to hypothalamus distribution into zones having no clear boundaries, its anterior and posterior parts are allocated, which, when irritated, exhibit directly opposite impaction the body. Instead, the changes in bioelectric activity of the trophotropic zone of hypothalamus in malerats of different age groups in normal conditions remain insufficiently studied. The withdrawal of bioelectric activity from the trophotropic zone of hypothalamus is in most cases the only indicator of determining the course of central nervous processes in the study of the functional state of the corresponding part of the brain.

Purpose. To identify age-related changes in bioelectric activity of the trophotropic zone of hypothalamus in male rats.

Methods. Experiments were carried out on non-linear white outbred male rats. The animals were distributed into studied groups using the classification of age groups of laboratory animals by Zapadniuk I.P. According to the classification male rats were divided into IV groups: I group (2.5 months) – the juvenile puberty period, II group (eight months) – the young age of the reproductive period, III group (fourteen months) – the mature age of the reproductive period, IV group (21 months) – rats of presenile age of the pronounced senile changes period (IV group). Rats of the studied groups underwent Electric Hypothalamus Test (EGtG) of the trophotropic zone. The corresponding hypothalamic zone bioelectric activity registration was carried out under the conditions of an acute experiment on a polygraph П6Ч-01 using standard electrophysiological equipment with a 16-bit analog-to-digital converter with a quantization frequency of 512 Hz (O.O. Bogomolets Institute of Physiology, Kyiv).

Results. In Juvenile male rats the highest percentage among other represented EGtG frequency components was the spectral power of the delta-range waves in trophotropic zone of hypothalamus. The males of the youngest age group showed the predominance of slow-wave synchronization processes in the form of predominance of low-frequency high-amplitude bioelectric activity in the trophotropic zone of hypothalamus. Instead, the age period changes resulted in significant changes indynamics of normalized spectral capacities of EGtG frequency components in the corresponding hypothalamus area. In young males, the functional activation of desinchronizing effect on bioelectric activity in this area of hypothalamus prevailed due to the predominance of the variation of the spectral power of the EGtG high-frequency components. Given the results of our study, where the highest percentage of alpha activity belongs precisely to rats of presenile age, this may be evidence of a certain peak in the brain maturation. However, in mature male rats, the prevalence of low-frequency oscillations and the predominance of delta-like activity in the EGtG, isolated from the trophotropic zone of the hypothalamus, which is evidence of the powerful synchronizing mechanisms functioning, were again observed.

Conclusion. It is shown that with age, the dynamics of normalized capacities of the EGtG frequency components in rats, isolated from the trophotropic zone of the hypothalamus, significantly changes. Registered age-related changes in the bioelectric activity of the trophotropic zone of hypothalamus of rats can be attributed to adaptive-compensatory modulation of central neurotransmission in general.


Keywords


anterior hypothalamus; Electric Hypothalamus Test (EGtG); normalized capacities of bioelectric activity; male rats; age

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